The brown ring test for nitrates depends on | Chemistry | SolveeIt

Question

The brown ring test for nitrates depends on

the reduction of nitrate to nitric oxide

oxidation of nitric oxide to nitrogen dioxide

reduction of ferrous sulphate to iron

oxidising action of sulphuric acid

Answer

the reduction of nitrate to nitric oxide

Explanation

Solution

The brown ring is obtained due to the formation of pentaaquanitrosonium ion. In this reaction reduction of nitrate ion by $Fe^{2+}$ ion takes places as

${NO_3 + 3Fe^{2+} + 4H ^+ -> NO + 3Fe^{3+} } + 2H_2O$
${ Fe^{2+} + NO + 5H_2O ->} \underset{\text{Brown complex}}{{[Fe(H_2O)_5NO]} ^{2+}}$

Chemistry Question on Classical Idea Of Redox Reactions – Oxidation And Reduction Reactions

Solution